The present invention relates to high-pressure integral tube coupling arrangements. More particularly, the present invention relates to such arrangements for coupling flexible hoses, such as a reinforced rubber hoses to metal tubes for use in systems such as vehicle brake and clutch systems.
In discussing the automotive industry, the Background of U.S. Pat. No. 5,037,142 states: xe2x80x9ca wide variety of connector devices have been utilized to connect tubes to hoses for conducting fluid therethrough or transmitting a hydraulic force through a column of oil contained therein. In many cases, specialized couplings are required which not only hydraulically connect adjacent tubes or pipes, hoses and other conduits in a fluid-tight manner, but also provide effective support while allowing relative movement of components and providing protection in relatively harsh environments.xe2x80x9d
Current methods for joining hoses to metal tubes still substantially rely on threaded couplings in which an externally threaded hollow nut is threaded into a internally threaded fitting to hold a flared tube tightly within the fitting. Since both the nut and the fitting must be machined, they are relatively expensive. In addition, making the connection is time consuming and labor intensive because it is not conveniently adaptable to automation. Moreover, quality control is difficult because there is the possibility of threaded components being joined without proper alignment so that threads are stripped, resulting in joints that leak and are subject to failure when operated at high pressures over long time periods of time in adverse environments. In view of these difficulties, there have been attempts to form couplings which do not require threaded components. Brazing a tube onto a hose fitting is one approach. Since these couplings are frequently exposed when used with brake systems, clutches and hoses, they are subject to environmental degradation because of moisture, road salt, wide temperature fluctuations and mechanical impacts and vibrations, all of which combine to accelerate corrosion. In order to protect brazed joints from corrosion, it is necessary to plate the assemblies which is in and of itself a relatively expensive undertaking. Moreover, these assemblies frequently require parts which have multiple elements each of which has the potential to provide a leak path and each of which must be handled and stored.
The technology of coupling hoses and tubes is now generally going to xe2x80x9cquick-connectxe2x80x9d type couplings in which all that is required to achieve a fluid tight connection is for two components being joined to be axially pushed toward one another, so that there is no need to rotate components of a coupling, one with respect to the other. When coupling metal tubes to rubber hoses, it is the practice to crimp the rubber hose within the coupling which is a rapid, reliable process requiring only a single metal-deforming step once the hose is inserted into the coupling. In order to further simplify assembly so as to reduce cost, it is desirable to simplify connecting the tube to a crimpable fitting.
In view of the aforementioned considerations, it is a feature of the present invention to provide new and improved tube-to-hose couplings which are reliable, inexpensive and yet require manufacturing steps which are minimal and do not introduce difficulties of their own.
In view of this feature and other features, the present invention is directed to a coupling arrangement for connecting a tube to a hose wherein the tube has a main portion and an insertion portion, the insertion portion being inserted through the fitting into the hose. The tube further has at least a first outwardly extending radial projection which cooperates with the fitting, the insertion portion of the tube extending beyond the radial projection to the terminus of the tube. The fitting has a first portion with a bore for receiving the tube therethrough and a second portion extending axially from the first portion for receiving the hose therein, with an interior surface on the first portion facing the second portion. The tube is disposed in the bore of the fitting with the outwardly extending projection abutting the interior surface on the first portion and the insertion portion extending into the second portion of the tube for insertion into the hose.
In a further aspect, the fitting includes a second abutment surface thereon facing away from the second portion for opposing axial movement of the tube toward the second portion of the fitting, and in a still further aspect, the portion of the tube engaged by the second abutment surface is on the first projection.
In a further aspect, the second abutment surface is on a portion of the fitting which is radially and axially deformed into abutment with the second abutment surface.
In still a further aspect, the second axially extending abutment is at a radially extending end of the fitting.
In a further aspect, the second portion of the fitting is a crimping collar for radially engaging the hose while the insertion portion of the tube is within the hose.
In still a further aspect of the invention, the main portion of the tube is covered with a layer of deformable protective material with the insertion portion and radially extending radial protection being uncoated. In accordance with this aspect of the invention, there is a metal-to-metal seal between the fitting and the uncoated radial projection. On the other hand, the definable protective material may be pressed into the fitting to provide a sealing area.